Better performance with tabs down...

[comsnark]

I run best with my tabs fully retracted, BUT that statement presumes the boat is fully on plane.

At 27mph, my boat wants some tab to stay fully on plane. If you upped your speed slightly, you may find a different imperical answer to your use of tabs.

 

[frosh coach]

Studman:

I purchased a 94 300 Dancer last season and only have 12x12 tabs. I jhad to run at 3600 to stay on plane. I was burning some serious fuel.

Your correct that they are to small. I spoke with someone from Bennett that said they should be 12x24. He also suggest that hey have the 3" side on them and have it point down.

I had a friend of mine cut me some 18x12 pcs of SS that im going to bolt & rivet to the current tabs. This will be my shoort term fix until I but 24x12 tabs. I have to move the actuator for those any really didn't want to start that.

I know most of you guys are running twins but I have a single engine and I am always fighting it listing to port.
I have the deploy the port tab to get her to ride level, it's a really pain
anyone know how to fix this problem? I was thinking os bigger tabs , mine are only 12 x 18

 

[hottoddie]

I bought my 1986 390 Express with 454 Crusaders last year. It had the stock 28" X 12" tapered style Bennett tabs. The trailing edge was 23" wide. To get up on plane you had to run quite a while @3600 rpm and maintain 3300 rpm with the 4 barrel's open to stay on plane @22mph. Flow scans showed fuel burn at 3300 rpms to be 34 gph. That's .65 mpg. Over the winter I changed the tabs to 30" X 15" (modified the 30" X 12"). Also modified the old 28" X 12" and cut them down to 12" X 12" and installed them in fixed position at the bottom of the V on the hull. Results: 22 mph @ 3100 rpm, 24 gph (.92 mpg) with 50% tabs (using Bennett indicators). Much more level and comfortable ride. It's like a diffent boat. I have made similar mods to my last 2 boats with similar results. Clearly Sea Ray and most boat manufactuers under tab their boats, don't know why, cost I guess.

 

[Lucky's]

That's great info and amazing results! I believe from some prior posts I've seen on here that it's possible to change or modify the size of my tabs without having to change out my pump and actuators. Is that right? Mine are flat (I believe), and I like the idea of getting tabs that have the 90 degree angle on the ends, angled down to channel more and thrust out the back instead of off to the sides. This is something I think I want to do...

 

[wakeup 19]

Studman:

I purchased a 94 300 Dancer last season and only have 12x12 tabs. I jhad to run at 3600 to stay on plane. I was burning some serious fuel.

Your correct that they are to small. I spoke with someone from Bennett that said they should be 12x24. He also suggest that hey have the 3" side on them and have it point down.

I had a friend of mine cut me some 18x12 pcs of SS that im going to bolt & rivet to the current tabs. This will be my shoort term fix until I but 24x12 tabs. I have to move the actuator for those any really didn't want to start that.

I have a 92' 300 with same engines. I maybe a little lighter but I can stay on plane at 2800 and run 31pmh at about 33-3400. 10.5 beam and 9k lbs but I am usually carrying a dinghy with motor on an extended platform. Can't believe the diff. Did I email you earlier in the year about this? Rob

 

[Studman]

Well I run from Stratford to Port Jeff the other day, pretty calm seas
I can get up on plane with no problem about 3500 rpm,s then I backed it down to 2900-3000
I was able to stay at 2900 rpm, doing 20-21 kts and burning 14.3 gph
I pushed it up a bit to see what would happen and at 3400 rpm's 25-26 kts, and 17.2 gph
2 guys, 1/2 tank of fuel, 3/4 tank of waste ( was cleaning it out ) and 3/4 fresh water
oh just a little port tab to keep the boat level

then on the way back I wanted to see what WOT would be like and was only able to get to 3800rpm and 29kts.
not sure why, I might have had a head wind but will try again to see what happens

 

[hottoddie]

If your boat is fuel injected, then running the rpm's up to 3300-3500 won't cause a huge increase in fuel burn. The older boats with 4 barrell carbs have the secondary barrell's cut in around 3100 rpm's. If you have flow meters like I do you can tell when the secondaries start to open. It is very beneficial to have the boat run on plane in at a decent trim angle for efficiency and visibility. With gas around $4 or more it's even more important. My 390 last year at full throttle @4400 rpm would burn 56 gph at 33mph (about .59 mpg). Now at 22 mph and .92 mpg I am very pleased.

 

[sam]

No regrets your engine should run at least 4600 rpm wide open. If not you might need some engine work like fuel filters, tune up. That should help if not you might need compressing test done.

 

[sea salt]

I was able to stay at 2900 rpm, doing 20-21 kts and burning 14.3 gph
I pushed it up a bit to see what would happen and at 3400 rpm's 25-26 kts, and 17.2 gph

You were more efficient at the higher RPMs ( ~1.43 mpg vs ~1.48 mpg). Not by much, but more effecient non the less. Probably because at the higher speed you had the hull higher up on plane and out of the water a bit more.

 

[frosh coach]

Rob:

Yes we spoke about this. I hopefully splash this weekend and will let you know the results.

I have a 92' 300 with same engines. I maybe a little lighter but I can stay on plane at 2800 and run 31pmh at about 33-3400. 10.5 beam and 9k lbs but I am usually carrying a dinghy with motor on an extended platform. Can't believe the diff. Did I email you earlier in the year about this? Rob